1. Field of the Invention
The present invention relates to a system that remotely controls a controlled apparatus using a radio remote controller and, more particularly, to power saving for the radio remote controller in the case in which monitor data is transmitted to the radio remote controller from the controlled apparatus.
2. Description of the Related Art
As an example of a system that remotely controls a controlled apparatus using a radio remote controller, there is known a hot water supply system that is adapted to remotely control a water heater main body using a radio remote controller. In the hot water supply system, power is supplied to a reception unit of the radio controller intermittently to realize power saving for the radio remote controller (see, for example, Japanese Patent Application Laid-Open No. 4-192996).
In such a hot water supply system, when a switch of the radio remote controller is operated, an interval from turning off power supply to the reception unit until turning on the power supply next is set as a first power OFF time. After that, when switching operation for the radio remote controller is not performed for a predetermined time or more, an interval from turning off the power supply to the reception unit until turning on the power supply next is set as a second power OFF time longer than the first power OFF time. This makes it possible to, when switching operation is performed, immediately receive monitor data indicating an operation state of a water heater that changes according to the operation. In addition, when switching operation is not performed, time for keeping the power supply off is extended to realize further power saving.
Here, in the conventional hot water supply system described above, the radio remote controller switches time for keeping the power supply to the reception unit off between the first power OFF time and the second power OFF time. When packet data transmitted from the radio remote controller is received, the water heater main body grasps that the first power OFF time and the second power OFF time is switched.
In this case, the water heater main body can grasp a length of time for keeping the power supply to the reception unit of the radio remote controller off (the first power OFF time or the second power OFF time). However, the water heater main body does not grasp time when the power supply is turned off. Therefore, when the water heater main body transmits monitor data to the radio remote controller at arbitrary timing, in order to make it possible to receive the monitor data on the radio remote controller side, the water heater main body transmits monitor data attached with a preamble exceeding the time for keeping the power supply off to the radio remote controller.
In this case, in order to set a length of the preamble to exceed the first power OFF time or the second power OFF time in the radio remote controller, the water heater main body is required to store data of the first power OFF time and the second power OFF time in the radio remote controller in a memory in advance. Thus, when the setting of the first power OFF time and the second power OFF time in the radio remote controller is changed, processing for changing the data of the first power OFF time and the second power OFF time stored in the memory is also required in the water heater main body.
Therefore, it is difficult to easily and flexibly change time for keeping power supply to the reception circuit of the radio remote controller off according to a form of use and design specifications of the water heater main body, a state of use of the radio remote controller, or the like to thereby realize further power saving for the radio remote controller.